Process of manufacturing sublimed white lead.



L. S. HUGHES. Pocss op MANUPAOTUBING SUBLIMBD WHITE LEAD.

APPLICATION FILED SEPT.21,`1909. I 975,867, Patented Nov,15,1910.

ATTORNEY CIK rrn srATns PAT K ICF.

LOUIS s. HUGHEsoF JOPLIN, MISSOURI, AssIGNoR To PICHER LEAD COMPANY, oF

JOPLIN, MISSOURI, A CORPORATION OF MISSOURI.

PROCESS or MANUFACTURING sUBLIMED WHITE LEAD.

speeication of L ettersratent. Paten-ted NOV, 15, 1910 Application Yfiled September 21, 1909. Serial No. 518,740.

To allr ibho'm it may concern:

rating the metallic fume from the gases by Be it known that I, LoUIs S. HUeHns, a x screening.

citizen of the United States of America, residing in J oplin,inV the county of Jasper', in the State of Missouri, have invented a certinl new and useful Improvement in Processesl of Manufacturing Sublimed White Lead, of which the following is a true and exact description, reference b'eing had to the accompanying drawings, which form a part thereof. v

My invention relates to the manufacture of sublimed white lead, a well known pig# ment basis, consisting essentially of lead sulfate. This pigment has heretofore been, I believe, most successfully manufactured in 'furnace plantsconstructed' in substantial accordance with the general structure and improvements described in the patents to Bartlett numbered 515,039 and 515,040, granted February th, 1894, and in the way described in said patents.' f

`As heretofore' practiced thel process 'of manufacturing sublimed white lead as carried out in a plant such as that described by Bartlett was assumed to require a high tem- 'perature in the furnaces a'nd Hue system Vzo leading therefrom to the screen system, it being the understandingv that such /high temperature was necessary to the production of a pigment suiciently white in color and of a texture best adapted for pigment use.

I have discovered that, contrary to the un- Y derstanding and practice of those skilled in the art, the `high `temperatures heretofore l used in the. furnaces and flues do not Veither produce the best possible pigment or the largest pigment yield from the Vsulfid and other lead bearing materials used in the furnaces, and-I have further discovered that by so regulating the blast and draft of the system as to maintain a temperature inthe Hues -below'that at which the free oxygen in the Hue gases will combine with the SO, to form SO3 in any large proportion an increased yield of improved pigment is secured, and

my invention, broadly speaking, consists in treating lead suld ore andl otherlead bearing materials in low cupola blast furnaces to produce therefrom a high percentage ofbasic'lead sulfate fume passinglsaid fume in admixture .with the furnace gases. and a1r throughheated H ues maintained at temperatures below7 that at which any` considerable formationV of SO,4 occurs, ,andl finally sepa- Vhlgh temperature.

I will describemy process more fully n connection with the drawing forming parl of this specification and which illustrates in section a plant such as I have employed successfully in practicing my invention.

In this drawing, Fioure 1 shows the furnaces and first. part of the Hue and Fig. 2 shows, on a reduced scale, the rear of 4the Hue, the tower and the cooling and screening system. t

A, A, are the low cupola furnaces inclosed by water jackets a, andhaving tap holes B.

C C, are blast into the furnace through twyers C".

D, D, are charging apertures at the top of the furnace through which also enters the free air which passes with the furnace gases into the Hue.

E,'is the flue; .E, E', water jackets forming the side walls of the Hue above the furnaces, F, F, and F, F', are the pipes for feeding and withdrawing water to and from the jackets E.

G, is the tower into which the flue E o ens and in which the gases, etc., have a whir ing or turning motion before passing into the flue extension from which they pass to a cooling system indicated at I.

J is a suction fan through which the ases pass to the screen system indicated at I L.

The character and general mode of use of the plant indicated in the drawing are well known. I

As heretofore used a very hot and energetic combustion was maintained in the furnaces A, A, for the purpose and result of maintaining in the flue E and tower G a very Accurate determination of the Hue temperature was difficult in the oldpractice, and is still difiicult, and temperature observations were and are in practice madeby ascertaining the temperature in the tower G which was consistently maintained in the old practice above 1400o Fahrenheit, notV infrequently approximating 1800o Fahrenheit, while the Hue temperature in all cases'materially exceeded 2000o Fahrenheit through the greater part of its length. At these temperatures the free SO2 in the furnace gasesr combines freely with the free oxygen forming- S()3 which acts on the fume of Abasic lead sulfate Pb3S2O, or QPbSO-'l-PbO, uniting with the PbO and pipes from which air passes i converting it into the neutral'sulfate PbSO4 which is inferior tothe basic sulfate for piggment uses.

y lowering the combustion in the furnace so t at the measured temperature `1n tower G is maintained between 900 F. and 1400" F. and the flue temperature throughout the greater part of its Alength below 2000O F., I

Y ave discovered that I can secure a vpigment consisting substantially of the basic sulfate -and with complete elimination of carbonaceous im urities. In actual practice I have not foun it practicable to avoid localsuperheating in the tops of the furnaces but by ,maintaining the flue temperature at the low heat stated the percentade of neutral sulfate formed isinconsiderab e; Moreover' in ay process such as that carried out in the illustratedplant the'amount of oxidation which can be accomplished on the finely divided sulfid ore thrown on the top of the furnace ,char e. depends upon the amount of air `whic comes in contact with the ore unchanged and the uncombinedair entering the furnace tops and fines will be greatly iiicreased-as the temperature ofthe furnaces,` and conseguently thetemperature of the flue, is lowere hence b lowering the temperature of the furnace decrease the amount of products of combustionwhich the fine has 4 to carry off and also reduce the proportionate volume of such products hence a larger volume of uncombined air can and does enter the furnace tops and iue and. a larger roportion of the charge is converted into ead sulfate fume. This result-is in great part due also to the decrease inthe quantity of CO2 whlch, though inertis a di-luent which interferes with the combustion of the ore.

A ain I have discovered that the heat hereto ore/used in the lmanufacture of sublimed. lead-has an m'urious effect upon the tinctorlal -valueio -the pigment and that the basic lead sulfate produced by Iis no doubt my process has distinctl greater tinctoria value. I This ue to the fact that definite solid particles formed by condensation are larger l 1n mass the more slowly they form and it is well known that tinctorial strength is in all cases ro ortionate te the finenessof "the indivi u'a particles. My rocess involving the more rapid coolin an consequent vmorer rapid precipitation o thepigment, will of course produce finer particles. Again I have discovered that the lead sulfate pigment can be made Whiter in color'by my process lthan by the old high heat, treatment v owing to the Ifact that .the sublima-te always 'contains some trace of ferric oxid. This ferrie oXid is of low color strength unless supcrheatcd and .in the old high heat treatment it was supcrheated to a degree which noticeably impaired the whiteness of the igment while by my low heat treatment 1t 1s.

not given colr strength enough to seriously darken the product. In additlon to securing a larger proportion of sublimate from the charge used, a product not materially contamimited by neutral lead sulfate, a product of higher tinctorial Vahle and of whiter color, l have found that my product is less sor variable than that of the old treatment besulfate for use as a pigment whlch consists .inmaintaining yone or more lowl cupola blast furnaces in operation, feeding lead sul'd ore and other lead bearlng materials into said furnaces, passing the furnace gases .and

lead fume and burning'sulid .in admixt-ure'` with air through a heated flue system to complete the .oxidation of the sulid and elimlnate carbon, andfinall screening the furnace gases to se )arate t etlead sulfate fume, the improve Allmethod of producing the sulfate pigment" in greater proportionate quantity-to the sulfid ore and other lead,

bearing materials used land of `superior quahty, which consists 1n mamtammg the temperature ofthe tlues lat a point below -that at which .S03 will formin substantial andinjurious quantity 'from the union of 'SO2 and free oxygen inthe flue.

LoUIs s. HUGHES.

Witnesses.: j

J. EDWARD Vlfiznn,v 4RUBY SPARKS. 

